The present invention relates to an arrangement for effecting a very rigid connection between relatively thin sheet metal and a heavy member. A typical example of such a structure is the connection between fan blade members and the like with a central hub member by which the blade member is adapted to be connected to a rotating drive shaft or the like. Other examples of this type of structure are for bushings, sleeves and various types of fasteners.
As disclosed in my U.S. Pat. No. 4,245,960, problems with providing an interlocking structure between a relatively thin sheet of material with a relatively heavy member exist particularly when interconnecting a sheet metal fan blade member to a hub. As disclosed in this patent, a good structure for interlocking the sheet metal fan blade member to the hub included placing the sheet metal member on the hub which had a groove and an upstanding coaxial sleeve which snugly fits in the bore of the sheet metal blade member. Then with a suitable tool, a plurality of shear cuts are formed in the free end of the sleeve to divide the same into a plurality of axially extending segments with every other segment being crimped down to force a portion of the edge of the aperture into the groove. This provides an interlocking structure, which would transmit torque between the hub and the fan blade member. If the connecting line were not a circular groove but a linear groove, then the alternate deforming of the segments would prevent sliding motion along the connecting line between the sheet metal member and the heavier member.